[roll] Roll fuchsia [kstress] Update readme

With recent system assembly changes the stress tests must be included
to the build using --with-test

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1214344
Original-Revision: d640bc904d5c5afec10f04f9819203902627fd89
GitOrigin-RevId: 76e61d58cdb897b6415096936ffb6f3611947a4c
Change-Id: I8bf7e27820976adfc79b7714a84f44cd491d7022
diff --git a/stem b/stem
index f7a820b..916cf12 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="92a1a2e60b0cd81982ed581f5cc46987a5636f26"/>
+             revision="d640bc904d5c5afec10f04f9819203902627fd89"/>
   </projects>
   <hooks>
     <hook name="install-environment"